Improvement in galvano-plastic coatings of the interior of metallic tubes



UNITED STATES JOHN MATTHEWS, Jn.,

PATENT )Eiucln` or NEW YORK', N. Y.

IMPROVEMENT IN.GALVANO-PLASTICCQATINGS F THE INTERIOR 0F METALLIC TUBES.

Spccitication forming part of Letters'latent No. 28,590, dated June' 5, 1860.

tical section view of a piece of tubing andthe A apparatus employed in silvening its in terior.4 I Many attempts have been hitherto mad-e to silver the interior of lead and other tnbingemployed in mineral-water apparatus, and for other purposes, by the voltaic process; but it has hitherto been found impossible to 'effect a uniform 'deposition ot' thesi'lver throughout the whole length, or evento obtain any deposition beyond a shortrdistance from the ends ofthe tubing. v

, `The object of myinvention is to obtain by suchl process Ia uniform deposition of the silver on every part ofthe interior of av piece of tubing of'a'ny lengt-h; and to this end my inventionrelates to the employment as the bath or .decomposition-cell of the tube itself, and to the v juse,for the'purpose of conducting the galvanic j current and for replenishingv the supply of the coating metal, of a rod or wire, 'passin g through the tube in the direction of ts'length.

1 It consists, first, 'inthe extension or stretchingof thet'ubeand central conductor by means of screw-threads and nnts,or their equivalents, attachedto their ends, for the purpose of keeping them straight, and thereby providing for the more ready vinsertion of the-centrat conductor'withi'n the tube and for the prevention l of metallic Contact; secondly', in the use of non- =couducting supports between the interior of the tube and the exterior of the central conductor, for the purpose of preventing thecon- .duetor4 coming in contact with thc tube and preserving a uniform distance between them inall parts 3' thirdl y, in providing For the movement of the central con d uctor and its non-conductingsupports-within the tube to permit the deposition ofthe metal on all parts ot' the in terior of the tube, which could not take place if the supports were stationary.

' dition.

To enable others skilled in the art to. apply my invention, I will proceed todescribe it with reference to the drawing. v

' Arepresents a piece of lea-d tubing, which maybe of indefinite length,` undergoing the silvering process'on its interior surface. It` has temporar-ilynattached, by-soldering or otherwise, at its lower end, a flanged socket,B, and at its lupper end a socket, @,and each of the'said sockets has a screw-thread cut on its exterior, the thread on the Abelow the flange a. `D D' E F is a; strong lower socket being framing somewhat 'longer than the piece of tubing. The sockets B and C are fittedl to the cross-pieces E and F of the framing, and the flanged ofthe lower socket, B, bears against the bottom otthe crosspieee E, and a nut, G, is applied to the screwthread ot the upper socket, C, above the crosspiece F, for the purposeof stretching or exf tending the tube to a perfectly straight con- The tube should be kept as nearlyas practicable in anupright condition. The lower socket, B, is closed by a stufli'ng-box, H, through which passes the central conducting rod or Wire, -I, which passes longitudinally through the tube. The gland of this stuiing-box should be of hard india-rubber or other non-conducting substance, or hushed with vsuch substance,

to keep the conductor I insulated from the tube. The said 'conductor I is considerably longer than thc framing, so that it may extend through the ends thereof, and has screw-threads cut on its exterior for a considerable distanceV from its ends, and these screw-threads are titted with lnuts J and K outside of the two ends of the'framing, said nuts serving to keep the conductor stretched or lextended perfectly straight and out of contact with thetube, and also serving, by unscrewing one away from the fra-ming and screwing the other toward it, to

move the conductor longitudinally within the tube. Thecentral conductor, I, may be of solid silver,.or of copper coated with silver, as I propose to makeit serve not only as a conductor', but as a means of replcnishing the supply of silver for coating the interior of the tube, and it' made of copper coated with silveritscoat-- -in g will requireto be renewed after one or more y tubes' have been coated. The bottom piece, D', of the framing is made movable to afford convenience for insertingthe tube and central conductor.

b b are rings, of india-rubber or other nonducting material, tted tightly to the exterior of the conductor I at suitable distances apart, and itting loosely to the interior of the tube A, constituting the supports for keeping the conductor lout of contact with the tube. Instead' of these rings, a-strip of india-rubber may be wound spirally round the central conductor for the same purpose. v

c represents a wire for `connecting the positive pole of the battery with the lower end of the tube a, and d rcpresentsa wire for connect.- ing the negative pole of the battery with the upper endof the central conductor.

The process isv conducted in the following manner: The tube, having had the sockets B- and C attached to it, is lplacedin the framing from the bottom thereof, while -the bottom piece, D', is removed therefrom, and extend to a. straight condition lby screwing-down the nut G.' The central conductor, I, with the supporting-rings b b upon it, is then passed through the tube from the bottom and through thetop piece of the framing, and the gland of the stung-box H applied and'screwed up, after which the bottom piece, D', of the framing is 4put on,.and the nuts J and K put on the con ductor and screwed up closelyvto the framing, to stretch or extend the conductor to a perfectly straight condition. rlhe tube Ails then lled up withv the solution ofl silver, and the -eounections between the tube and conductor with the battery made bythe Wires cA and d, as before described, and the deposition of the silver in the interior surface of the tube A immediately commences, the deposit being uniform on every part of the said surface', except Wherethe non-conducting supports b come in contact with it, and as no deposit, or averyimperfect deposit, takes place on those parts, the conductor I is required to be frequently moved in a longitudinal direction to change the position of the, said supports. This maybeefected by unscrewing one of the n uts J K and screwing the other up or down by hand, as may be required; or a continuous movement of the said conductor and its non-conducting supports may be effected by some suitable mechanism applied to the nuts or-applied to the conductor in any other way. By the consta-nt or frequent shifting of the nonconducting supports within the tube.1 as above described,the deposit of sillver on the interior of the tube may be made of uniform thickness on every part covered by the silver solution, and such deposit maybe madeof such thickness as may be desired, according to the length of time that the process may be continued, the time necessary being determined by practice. v A quantity of solution may be poured into the tube at the top as often as is necessary to `make up for any loss by evaporation or the .2. 'The use of non-conducting supports-b I),`

applied substantially as'and for the purpose herein specified.

3. Providing for the longitudinal movement of the central'conductor and its non-conducting lsupports b b within the tube, substantially as and for the purpose herein set forth.

-JOHN MATTHEWS, JR.

Witnesses:

B. GrnoUsE,

LIVINGSTON. 

